In a saucepan, heat oil over medium-high heat. Add the onion to the saucepan for 5-8 mins until translucent.
Add garlic and spices (cumin, coriander, cinnamon, cayenne pepper), stirring until fragrant, 1-2 minutes.
Stir in carrots, celery and sweet potato. Add water, stock, tomatoes and chicken breasts.
Bring to a boil. Reduce heat and simmer, partially covered for 30 minutes or until chicken is fully cooked.
While cooking, drain the chickpeas. Add these to the pot after 20 minutes.
After the 30 minutes, remove chicken from soup and shred and return to pot along with the cavalo nero. Season with salt and pepper. Leave for another 5 minutes to simmer.
Serve with chopped coriander and a good squeeze of lemon.